An ileus is a decrease in intestinal motility not caused by a mechanical obstruction. The cause is usually abdominal or pelvic surgery, but other etiologies include medications (narcotics, anticholinergic drugs), abdominal inflammation (such as pancreatitis or peritonitis), electrolyte or metabolic abnormalities (hypokalemia, hypocalcemia, hypomagnesemia, hypothyroidism), and severe illness.

Symptoms of an ileus include diffuse abdominal pain, constipation or obstipation, lack of flatus, belching, nausea or vomiting, and inability to tolerate oral intake. Characteristic exam findings include abdominal distension, decreased bowel sounds, and abdominal tenderness.

Treatment is mainly supportive care, including intravenous (IV) fluids, correction of electrolyte abnormalities or acidosis, and pain management (limit narcotics for pain, as this can exacerbate the problem). If ileus is believed to be drug related, consideration should be given to the use of reversal agents (naltrexone or oral naloxone [Narcan] for opiate-induced ileus or neostigmine for anticholinergic-mediated ileus). If significant nausea or vomiting occurs or if significant distention is present, a nasogastric tube can be placed set to low intermittent wall suction. Oral intake should be restricted initially, with gradual advancement of diet as symptoms improve.